Reacting in a flash, Horn said he pulled his gun and shot Joe Martell six times.

Horn, 48, is on trial charged with second-degree murder. He and Martell, 34, clashed in an argument after the 2008 Chasco Fiesta in downtown New Port Richey. The men didn't know each other, but their groups of friends crossed paths earlier that day. They met again that night and ugly words were exchanged.

Prosecutors contend Horn voluntarily inserted himself into an argument that didn't involve him. Martell, according to witnesses, was feuding with Horn's brother-in-law and sister-in-law.

But taking the stand in his own defense Wednesday, Horn said Martell engaged him.

"He wanted to pick a fight with somebody," Horn testified.

Witnesses have differed on whether Martell punched Horn, and whether Martell was still charging when Horn pulled his gun. Those details could determine whether the jury sees the case as murder or legal self-defense under Florida's 2005 "Stand Your Ground Law."

Horn was calm and pointed on the stand. He frequently argued with prosecutor Jim Goodnow, often being the one asking questions.

Goodnow accused Horn of using his heart condition as a crutch to win sympathy with the jury, and suggested Horn had lost weight just to look better in court.

"Are you serious?" Horn replied.

He answered a question many who are following the trial have wondered about: Why did he carry a .45-caliber pistol to a parade where huge crowds were gathered, including families with children?

Horn ran down a list of U.S. incidents in which innocent people were killed in public places — a shooting at a Luby's cafeteria, a stabbing at a McDonald's.

"It happens all the time in this country," said Horn, who had a concealed weapons permit. "As a victim you don't get to choose."

He said he first saw Martell that night as Martell burst out the door of Hot Shotz bar, where Horn, his wife and their friends were waiting to go in. Martell bulldozed through the crowd, Horn said, knocking down a woman and pushing several others. That's when Martell got into a dispute with Horn's family members.

"Then he starts on me," Horn said. "I looked like a brute back then. I was a big fat guy with a crewcut. I told him, 'I can't fight you.'"

Then, he said, he lifted his shirt to reveal he was armed. "I'll shoot you," he told Martell.

"Did that stop him?" Horn's attorney, Keith Hammond, asked.

"Absolutely not," Horn said.

"What stopped him?" Hammond asked.

"Mr. Hicks (Martell's friend) grabbed him around the waist and pulled him back and pulled him away," Horn said.

Scott Hicks testified that he dragged Martell into a bar across the street to try to get him to calm down. But as soon as they got inside, Martell disappeared out a side door. Hicks and another friend chased after him.

Horn, who said he wanted to leave and was trying to get his group together, said he heard someone say "Oh no, he comes again."

From his vantage point, he said, he didn't know Martell's friends were following him to keep Martell from getting in a fight. All he saw was three men advancing toward him.

"I couldn't even imagine what was going on in their minds, rushing at me," he said.

Martell was shouting threats at him, and at one point told Horn, "You better pull that gun," Horn recalled.

Without warning, Martell punched him the head, Horn said, causing him to stumble back onto his wife. As he righted himself, he drew his gun and fired once into Martell's abdomen.

"I knew I couldn't sustain another punch like that," said Horn, who has a weak heart and has been on a transplant list. "He almost knocked me out."

Once upright, he said he fired again and again. Martell lunged forward, swiping at the gun, Horn said. One bullet struck him in the top of his shoulder; the others hit several places on his torso.

Goodnow pressed Horn about why none of the two dozen or so state witnesses recalled seeing any physical contact between Horn and Martell. Horn had no answer. The defense called three witnesses who said they did see the punch but had obstructed views of the incident.

According to Horn, he did the only thing he could do.

"Did you feel that your life was threatened?" Hammond asked him.

"Yes, absolutely," Horn said.

Attorneys are expected to give their closing arguments today before jurors begin their deliberations.

There is a reason why the air in Tampa Bay is filled with playoff talk. If Thursday night's 12-8 Bucs preseason win over the Jaguars is any indication, it's also going to be filled with footballs thrown by quarterback Jameis Winston.